How about buying a $20 PCIe card that has an internal SATA port or 2?
Its an idea, but as I already have a USB DVD drive or ISO files on a HDD, I think I will reduce my expense and use that until further notice.
You would need a Z77 to overclock the CPU, but then again there are some lower cost Z77 boards that would be worth considering. MSI for example have the Z77MA-G45 which from my local dealer costs £75. Like many Z77 boards it has an automatic overclock option which should take a 3570K to something in the low 4Ghz range without needing to resort to manual setting changes. The same dealer also has an OEM version of the 3570K for £168. I assume you can use the memory from your existing board. So your upgrade cost would be £243 minus whatever you can recover by selling the old motherboard and cpu. For this you would see a substantial boost in performance and a degree of power saving compared to your existing setup. The Z77MA-G45 would also resolve the issues regarding SATA port access and tick a few of the other boxes.
I think I would be able to sell my current CPU + mobo for about £130 which is why I was looking at a H77 mobo + i3 CPU with the intention of overclocking it because that would not be a huge expense, now I know that's not possible, I will stick with what I have and make do with a USB DVD drive, or ISO files on a HDD.
The real question is what you're planning on doing with any additional computing power you're looking to buy. For my purposes, I'm planning on doing a LOT of video re-encoding soon, so getting a little boost to 4.2GHz on my i7-3770K was worth the extra money. I also try to keep my motherboard for a long time between system upgrades. My previous X38 based motherboard had seen several different configurations around it over the past 4 years. If you've got any number crunching intensive apps, then you'd likely be better off saving up a little bit and getting a Z77+i5-3570K system. With a decent heatsink, you should be able to get 4.2-4.3GHz while still keeping noise levels in the spirit of these forums.
Thanks for the info Nick.
I only use my PC for browsing the internet, playing with documents, occasional video editing, watching movies and playing PC games. The games are the only thing that is stressful for the CPU, but now its overclocked and I have had a bit of a look around the internet there doesn't seem to be any point in upgrading at the moment.
Although "wprime" is a long way short of being a true indication of CPU performance whilst playing games, I have tested mine and its fractionally faster than a stock i5 2500K or a Phenom II x4 975 (because it seems that "wprime" doesn't use L3 cache, its all about clockspeed). I have also just tightened up the timings on my RAM which will help a little as well.
I have thought of one other possibility, I am sure many people will have seen SATA cables with a 90 degree connection (I have several), if I can find somewhere that sells them with the 90 degree angle facing the other way, that will work and then this thread will be dead and buried.